Disclosed herein is an apparatus and method for image production device media hold down transport air flow.
Presently, image output devices, such as printers, multifunction media devices, xerographic machines, ink jet printers, and other devices produce images on media sheets, such as paper, substrates, transparencies, plastic, or other media sheets. To produce an image, marking material, such as toner, ink jet ink, or other marking material, is applied to a media sheet to create an image on the media sheet.
In image output devices, it is common to transport media sheets from one processing station to another, for example from an image transfer station at a photoreceptor to a fuser in a xerographic machine. Typically, such sheet transporting uses conventional multi-belt vacuum belt transport systems. Substantial vacuum pressure is applied from a vacuum plenum through holes in each vacuum belt and in a concentrated manner onto an image carrying substrate being transported. Such substantial vacuum pressure is desirable in order to provide adequate control over each such substrate or sheet. Furthermore in other applications where vacuum belt transport systems are used to transport sheets under direct marking print heads, maintaining a high degree of sheet flatness and excellent motion control are required.
Unfortunately, open port leakage created by running sheets smaller than the plenum width reduces the hold down pressure available to hold the sheets flat. Current systems use multiple chambers with separate air sources or impedance balancing to reduce the pressure drop. However, separate air sources are expensive and can limit the subdivision across the transport width. Furthermore, impedance balancing can help reduce the leakage, but it also reduces the acquisition flow for the wider sheets. Internal cross process chamber gating or valving can also be implemented. However, internal cross process chamber gating and valving requires a very low impedance to air flow and can get very complex if multiple chambers are incorporated along the process length.
Thus, there is a need for an apparatus and method for media hold down transport air flow in an image production device.